Buffer management is a core component of a computer system and its operating system. A buffer management scheme may adopt a specific buffer replacement policy to improve the performance of the computer system or an application (e.g., a file system or a database system). For a computer using conventional disk-based storage system, many buffer replacement policies mainly aim at reducing the rate of buffer misses which may cause excessive accesses to the disks. To minimize the miss rate, the conventional buffer replacement policies may place equal emphasis on both the read and write operations, and may not distinguish the impacts to the buffer memory from these read and writes operations.
Comparing to the conventional disk-based storage systems, flash disks may have a read-write asymmetry, which means a write operation on a flash disk may be an order of magnitude slower than a read operation on the flash disk. The conventional buffer replacement policies may give higher priority to dirty pages, and are mostly based on the current page state of the buffer pages. However, these conventional buffer replacement policies that are designed for disk-based storage systems may no longer be optimized for flash-based storage systems.